Last October, Softbank officially bought 70 percent of Sprint, promising to invest $20.1 billion in Sprint. Of that sum, $12.1 billion was said to be dedicated to Sprint shareholders with $8 billion on the balance sheet.

The Sprint-SoftBank-Clearwire deal was on track for a decision from the Federal Communications Commission by May, but that could be up in the air now.

For now, the nation's fourth largest wireless provider assured shareholders in a statement that they "need not take any action at this time in response to DISH’s proposal pending review by Sprint’s Special Committee."

Bank of America-Merrill Lynch will act as a financial advisor to the special committee with Shearman & Sterling LLP retained as its legal counsel.

We are pleased that the Sprint Board of Directors has formed a special committee to review our proposal. We are available to meet with Sprint's Board, management and advisors to discuss our plans and our willingness to commit to financing. We are confident that the Sprint Board will share our view that this proposal is superior on several fronts by offering Sprint shareholders greater value with a higher price and more cash, while also creating the opportunity to participate meaningfully in a combined, and competitively unique, DISH/Sprint.

Our proposal creates a company with an industry-leading spectrum portfolio and the only company that can offer customers a fully-integrated, nationwide bundle of in- and out-of-home video, broadband and voice services while unlocking the full potential of Sprint’s Network Vision. Additionally, the combined national footprints and scale of DISH/Sprint will provide substantial benefits to the American public by bringing improved broadband services to millions of homes with inferior or no access to competitive broadband services.